U.S. patent application number 11/174055 was filed with the patent office on 2006-01-12 for folding tool with blade locking mechanism.
This patent application is currently assigned to Mentor Group LLC. Invention is credited to Kenneth Steigerwalt.
Application Number | 20060005397 11/174055 |
Document ID | / |
Family ID | 35539783 |
Filed Date | 2006-01-12 |
United States Patent
Application |
20060005397 |
Kind Code |
A1 |
Steigerwalt; Kenneth |
January 12, 2006 |
Folding tool with blade locking mechanism
Abstract
A hand tool such as a multi-bladed folding knife incorporates a
lock back mechanism that is interconnected with springs extending
parallel to the knife body. The springs apply biasing force to the
lock back mechanism associated with the primary blade, and also on
secondary blades if used.
Inventors: |
Steigerwalt; Kenneth;
(Orangeville, PA) |
Correspondence
Address: |
IPSOLON LLP
805 SW BROADWAY, #2740
PORTLAND
OR
97205
US
|
Assignee: |
Mentor Group LLC
|
Family ID: |
35539783 |
Appl. No.: |
11/174055 |
Filed: |
July 1, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60586967 |
Jul 8, 2004 |
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Current U.S.
Class: |
30/152 |
Current CPC
Class: |
B26B 1/042 20130101 |
Class at
Publication: |
030/152 |
International
Class: |
B26B 3/06 20060101
B26B003/06; F41B 13/02 20060101 F41B013/02 |
Claims
1. A folding knife, comprising: a handle having first and second
opposed side walls held in a spaced-apart arrangement to define a
slot therebetween; a first blade having a working portion and a
tang portion pivotally attached to the handle, said first blade
movable between a closed position and an open position; a first
spring member disposed between the first blade and one of said side
walls, and a second spring member disposed between the first blade
and the other of said side walls; a lock bar disposed between said
first and second spring members, said lock bar having a first blade
engaging surface on a first end; and a first pin with opposite ends
extending into said handles and extending through bores in said
spring members and said lock bar, wherein the diameter of the bores
in said spring members is greater than the diameter of said first
pin, and a second pin with opposite ends extending to said spring
members and extending through a bore in said lock bar between said
first pin and said first end of said lock bar.
2. The folding knife according to claim 1 further including second
and third blades, each having a working portion and a tang portion,
said second and third blades pivotally attached to the handle at
the opposite end from the first blade and movable between open and
closed positions, wherein said first blade lies between said second
and third blades when said first, second and third blades are in
the closed position.
3. The folding knife according to claim 2 wherein a rearward end of
said first spring member makes contact with the tang portion of
said second blade and exerts pressure thereon.
4. The folding knife according to claim 2 wherein a rearward end of
said second spring member makes contact with the tang portion of
said third blade and exerts pressure thereon.
5. The folding knife according to claim 1 wherein said spring
members exert pressure on the first blade engaging surface of said
lock bar through the interconnection between said spring members
and said lock bar with said second pin.
6. The folding knife according to claim 5 wherein said lock bar is
pivotal about said first pin.
7. The folding knife according to claim 6 wherein when said first
blade engaging surface locks said first blade in said open
position, and wherein said lock bar may be pivoted about said first
pin to unlock said first blade to allow said first blade to be
moved to said closed position.
8. The folding knife according to claim 6 wherein when said lock
bar is pivoted about said first pin, said first pin does not make
contact with said spring members.
9. In a multi-bladed knife having an elongate body with a forward
end and a rearward end, the body formed by two opposed side walls
forming a channel therebetween, and a primary blade pivotally
attached to the body at the forward end, and first and second
secondary blades pivotally attached to the body at the rearward
end, the improvement comprising: a first spring member disposed
between the blades and one of said side walls, and a second spring
member disposed between the blades and the other of said side
walls; a lock bar disposed between said first and second spring
members, said lock bar having a blade engaging surface on a first
end for engaging a tang portion of said primary blade when said
primary blade is in an open position; and wherein, said first
spring member applies biasing force against a tang portion of said
first secondary blade, said second spring member applies biasing
force against a tang portion of said second blade, and wherein both
of said spring members apply biasing force against said lock
bar.
10. The multi-blade knife according to claim 9 including a first
pin having its opposite ends in the opposed side walls and
extending through bores in said spring members and said lock bar,
wherein the bores in said spring members have a greater diameter
than the diameter of the first pin.
11. The multi-blade knife according to claim 10 including a second
pin located forwardly of said first pin, said second pin having a
first end in the first spring member, and a second end in said
second spring member, and said second pin extending through said
lock bar.
12. The multi-blade knife according to claim 11 wherein said lock
bar is pivotal about said first pin.
13. The multi-blade knife according to claim 12 wherein biasing
force from both of said spring members is transmitted to said lock
bar through said second pin.
14. The multi-blade knife according to claim 13 wherein said lock
bar is movable between a locked position in which said blade
engaging surface engages said tang portion of said primary blade to
lock said primary blade in the open position and an unlocked
position in which said blade engaging surface disengages said tang
portion of said primary blade so that said primary blade may be
moved to said closed position.
15. A folding knife, comprising: a handle having forward and
rearward ends and first and second opposed side walls held in a
spaced-apart arrangement to define a slot therebetween; a primary
blade having a tang portion pivotally attached to the handle at the
forward end thereof, and first and second secondary blades each
having a tang portion pivotally attached to the handle at the
rearward end thereof; primary blade locking means for locking said
primary blade in an open position, said primary blade locking means
comprising a lock bar pivotally mounted between said primary and
secondary blades, and spring means for applying biasing force
against said lock bar.
16. The folding tool according to claim 15 wherein said spring
means further comprise first and second spring members disposed on
opposite sides of said primary blade between said primary blade and
said respective first and second opposed side walls.
17. The folding tool according to claim 16 further including a
first liner disposed between said first side wall and said first
spring member, and a second liner disposed between said second side
wall and said second spring member.
18. The folding tool according to claim 17 including a lock bar
pivot pin extending through bores in said first and second spring
members and a bore through said lock bar, and said lock bar pivot
pin having its first end extending into said first liner and its
second end extending into said second liner, wherein said bores in
said first and second spring members are larger than the diameter
of said pin.
19. The folding tool according to claim 17 including a connector
pin extending through said lock bar forwardly of said lock bar
pivot pin, and said connector pin having its first end extending
into said first spring member, and its second end extending into
said second spring member.
20. The folding tool according to claim 19 wherein pressure from
said spring members is transmitted to said lock bar through said
connector pin.
Description
FIELD OF THE INVENTION
[0001] This invention relates to hand tools such as knives and
multitools that incorporate folding implements, and more
specifically to a blade or implement locking mechanism for use in
such tools that facilitates secure locking of the implement in the
open or extended position.
BACKGROUND
[0002] Many types of hand tools such as knives and multitools
incorporate folding mechanisms that allow an implement to be moved
between a folded position in which the implement is safely stowed
in the tool handle, and an extended position in which the implement
is ready for work. One typical example of such a folding tool is a
knife having a folding blade. The knife handle typically has two
opposed handle portions defining a blade-receiving groove. A blade
pivots on a shaft attached to the handle such that in a folded
position the blade is stowed with the cutting portion of the blade
retained safely in the groove, and such that in an extended
position the blade is extended away from the handle, ready for use.
Foldable knifes are ubiquitous.
[0003] To increase the safety of folding tools such as knives, many
such tools incorporate locking mechanisms of one type or another.
When the knife blade pivots into the open position, it's pivotal
movement is stopped with a blocking mechanism such as a transverse
blade stop pin housed in the handle. Often a locking mechanism is
included that prevents the blade from unintentionally pivoting back
from the open into the closed position. There are many types of
locking mechanisms. One common type is a "liner lock." This kind of
mechanism relies upon a resilient lever formed as part of a handle
liner. When the blade is pivoted to the open or extended position,
the resilient lever engages a cooperatively formed shoulder on the
blade and thereby locks the blade in the open position. Another
typical locking mechanism is a cross-bolt mechanism such as that
described in U.S. Pat. No. 5,822,866. As detailed in the '866
patent, which describes an automatic opening knife, the cross-bolt
mechanism includes a locking body that has a cylindrically tapered
side wall portion. When the blade is extended to the open position,
the tapered side wall portion of the locking body is urged by a
compression spring into a locking position in which the locking
body wedges between an engagement surface on the blade and a bore
in the handle to lock the blade in the open position.
[0004] There are other types of blade locks in addition to the
locking mechanisms just described. Another common type of locking
mechanism is called a "lock back" mechanism. While there are
variations in the structure for a lock back, in most lock back
mechanisms a latch bar held between the handles at the upward side
thereof pivots on a pivot pin extending through the latch bar and
having opposite ends connected to the handle halves. When the blade
or other implement is in the extended position, a spring mounted in
the rearward portion of the handle (between the handle halves)
applies upwardly directed pressure on the latch bar rearward of the
pivot, urging the forward end of the latch bar--that is, the end of
the latch bar on the opposite side of the pivot pin from the
spring--into a locking engagement with the blade. The forward end
of the latch pin typically includes a portion that engages a notch
in the blade tang. The blade is unlocked by pushing downwardly on
the rearward end of the latch pin at a notch in the
handles--against the spring force, to cause the forward end of the
latch bar to pivot upwardly and disengage the blade tang. It will
be appreciated that a significant amount of space is required to
house the springs and associated structures used to drive such lock
back mechanisms.
[0005] A very traditional multi-bladed folding knife known as the
"Whittler Pattern" has three blades: a single primary cutting blade
on one end, and two secondary blades on the other end. While these
knives have been manufactured for many years, given structural
constraints it has been difficult to make such knives with reliable
locking mechanisms for the primary cutting blade.
[0006] There is a need therefore for improved locking mechanisms
for folding hand tools, and in particular improved lock back
mechanisms. Lock back mechanisms for multi-blade folders such as
the Whittler Pattern are needed.
[0007] The present invention relates to a hand tool--typically
embodied as a knife--that incorporates a lock back-type locking
mechanism for securely locking the implement such as a blade in the
open position, and for releasing the lock to allow the implement to
be folded back into the closed position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention will be better understood and its numerous
objects and advantages will be apparent by reference to the
following detailed description of the invention when taken in
conjunction with the following drawings.
[0009] FIG. 1 is a perspective view of a hand tool--in this case a
multi-blade folding knife--that is exemplary of the type of hand
tool that incorporates a lock back mechanism according to the
present invention. In FIG. 1 the knife blades are all stowed in the
closed or folded position.
[0010] FIG. 2 is a perspective view of the knife shown in FIG. 1
with the three blades in the fully extended or open positions, or
in an intermediate position.
[0011] FIG. 3 is an exploded perspective view of the knife shown in
FIG. 1, illustrating some of the component parts.
[0012] FIG. 4 is a top plan view of the knife shown in FIG. 1 with
the three blades extended into their open positions.
[0013] FIG. 5 is a side elevation view of the knife shown in FIG. 4
with the knife handle and liner on the near side shown in phantom
lines to illustrate the internal structures of the knife. In FIG.
5, two blades shown in their fully extended positions and one blade
is shown in two different positions to illustrate operation of a
spring.
[0014] FIG. 6 is a bottom plan view of the knife shown in FIG. 4
with the three blades extended into their open positions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] A preferred embodiment of a hand tool 10 incorporating a
locking mechanism in accordance with the illustrated invention is
shown in the figures. Although the invention is described with
respect to its embodiment in a particular type of tool--a
knife--and even then a particular type of knife--a multi-bladed
knife--it will be appreciated that references to this type of a
knife, and indeed this particular type of hand tool, are for
illustrative purposes to describe the invention. Those of ordinary
skill in the art will appreciate that the invention claimed herein
is not limited to knives, but instead extends to any hand tool
having the features claimed herein.
[0016] With particular reference now to FIGS. 1 and 2, knife 10
includes a handle 12 and three blades 14, 16 and 18. The knife 10
shown in the figures is a traditional Whittler Pattern--a
multi-blade folding knife that has one primary cutting blade at one
end, and two secondary blades at the other end. Handle 12 includes
two side wall portions or handle halves 20 and 22 that are held
parallel to one another in a spaced apart relationship with various
screws and the like to define a blade receiving groove therebetween
for receiving blades 14, 16 and 18 when they are folded into the
closed position as seen in FIG. 2. Each of the blades 14, 16 and 18
is pivotally attached to the handle so that the blades are pivotal
between the open position of FIG. 1 and the closed position of FIG.
2. Specifically, blade 14 is pivotally attached to handle 12 with a
pivot shaft 24 that has its opposite ends fixed to the handle
halves. Likewise, blades 16 and 18 are pivotally attached to handle
12 with a common pivot shaft 26 that has its opposite ends fixed to
the handle halves at the opposite end of the handle from pivot
shaft 24. Appropriate spacers are incorporated into knife 10 to
define separate blade receiving slots in handle 10 to accommodate
the three blades in their folded position, as detailed below. It
will be appreciated that blades 16 and 18 pivot between their open
and closed positions in the opposite direction from blade 14. When
the three blades 14, 16 and 18 are in the closed or retracted
positions shown in FIG. 2, the working portions of the blades are
safely stowed in the blade-receiving grooves in the handle 12, with
blade 14 nested between blades 16 and 18.
[0017] As detailed below, blade 14 is the only blade in knife 10
that may be locked with the locking mechanism according to the
illustrated invention. As such, blade 14 is sometimes referred to
as the "primary blade." Blades 16 and 18 are sometimes referred to
as "secondary" or "minor" blades. It will be appreciated that the
type of blades shown in the figures (i.e., blades 14 and 16 are
conventional knife blades and blade 18 is a conventional gut hook
blade) are for illustrative purposes, and the invention is not
limited to use with any particular type of blade or implement. As
used herein, relative directional terms such as forward refer to
the end of the knife on which primary blade 14 is mounted.
"Rearward" is therefore the opposite longitudinal end of knife 10
where blades 16 and 18 are mounted.
[0018] Immediately inward of the handle halves 20 and 22 are liners
28 and 30. Liner 28 is positioned next to handle half 20 and is
thus sandwiched between handle half 20 and other structures
described below. Similarly, liner 30 is positioned next to handle
half 22 and is sandwiched between handle half 22 and other
structures.
[0019] Both liners 28 and 30 have stepped down portions at the
areas identified with reference numbers 32 and 34, respectively.
These stepped down portions result in relatively thinner sections
of the liners, identified with reference numbers 36 and 38,
rearward of the stepped down portions 32 and 34. The relatively
thinner liner sections are for receiving spring members 40 and 42.
It will be understood that the stepped down portions may be formed
by removing material from the liners, or by using thicker, separate
spacers to define the thicker, forward end of the liners. The
structure and function of spring members 40 and 42 will be
explained in greater detail below. Both spring members are
fabricated from a resilient material such as titanium or tempered
steel to provide biasing force on blades 16 and 18, and also a
biasing force for use with the lock back mechanism.
[0020] A lock bar 44 is positioned intermediately between handle
half 12, liner 28 and spring member 40 on the one side, and handle
half 14, liner 30 and spring member 42 on the opposite side. Each
of the handle halves 12 and 14, the liners 28 and 30, and the
spring members 40 and 42 are cut out at a notched section 46 to
expose lock bar 44 and allow its use to lock and unlock primary
blade 14. A spacer bar 48 is mounted in an intermediate position
rearward of lock bar 44. Lock bar 44 is not notched in the notched
section 46.
[0021] Reference is now made to the exploded view of knife 10 shown
in FIG. 3 where it may be seen that the pivot shafts 24 and 26
extend through bores formed cooperatively in the various component
layers of knife 10. Pivot shaft 24 thus extends through bores
formed in handle half 20, liner 28, blade 14, liner 30 and handle
half 22. Similarly, pivot shaft 26 extends through bores formed in
handle half 20, liner 28, blade 16, spacer bar 48, blade 18, liner
30 and handle half 22. The bores in these components are shown in
the drawings but are not identified with reference numbers; it will
be understood that when the components shown in FIG. 3 are
assembled into the finished knife 10 as shown in FIG. 1, all of the
bores align so that the pivot shafts extend through the aligned
bores. The pivot shafts assist in holding the knife components
together in a conventional manner, and may for example be threaded
on one end if desired.
[0022] The locking mechanism that is incorporated into knife 10 and
which locks primary blade 14 in the open position is identified
generally as locking mechanism, or lock back mechanism 60, and is
comprised of several structural components including springs 40 and
42, lock bar 44, and the pins that mount these structures to the
knife.
[0023] Spring members 40 and 42 extend along the upper or "spine"
edge of knife 10 and are mounted in place with several pins
beginning with first pin 62, which in assembled knife 10 extends
through bore 62a in handle half 20, bore 62b in liner 28, bore 62c
in spring member 40, bore 62d in spacer bar 48, bore 62e in spring
member 42, bore 62f in liner 30, and finally bore 62g in handle
half 22. A second, forward mounting pin, referred to herein as
second pin 64 or lock bar pivot pin 64, extends through springs 40
and 42 in a position toward the opposite end of the springs--that
is, toward the forward end of the knife 10. Thus, lock bar pivot
pin 64 in assembled knife 10 extends through bore 64a in handle
half 20, bore 64b in liner 28, bore 64c in spring member 40, bore
64d in lock bar 44, bore 64e in spring member 42, bore 64f in liner
30, and finally bore 64g in handle half 22. Although in the
illustrated embodiments first and second pins 62 and 64 have
opposite ends extending into handle halves 20 and 22, these pins
need not extend into the handle halves and may instead have their
opposite ends extend into or resident in the bores in the liners 30
and 32.
[0024] Bore 62c in spring member 40, and bore 62e in spring member
42 are sized so that the diameter of the bores is only very
slightly greater than the diameter of pins 62 and 64, respectively
to allow the pins to be tightly inserted into the bores. As such,
the pins will slide into the bores to facilitate assembly of the
knife 10, but there is a close tolerance between the outer surface
of the pins and the bores.
[0025] Bore 64c in spring member 40 and bore 64e in spring member
42 are formed so the diameter of these bores is oversized relative
to the outer diameter of lock bar pivot pin 64. Thus, the diameter
of bores 64c and 64e formed in spring members 40 and 42,
respectively is greater than the outer diameter of lock bar pivot
pin 64 where the pin extends through these bores, resulting in a
relatively greater tolerance (i.e., space) between the outer
circumference of pin 64 and the sides of bores 64c and 64e. As a
result, the lock bar pivot pin 64 has some "float" or room for
movement in bores 64c and 64e. As detailed below, this allows the
lock bar 44 to operate. The bores 64c and 64e are preferably about
0.032 inches greater in diameter than the outer circumference of
lock bar pivot pin 64, although the amount of oversizing may be
varied without adversely effecting operation of lock mechanism 60.
As an example, the bores 64c and 64e could be oval in shape to
allow the pin to move in the bores. Bore 64d in lock bar 44 is the
same diameter as pin 64 so there is a close tolerance between lock
bar pivot pin 64 and lock bar 44.
[0026] Lock bar 44 is mounted in knife 10 between spring members 40
and 42 with a connector pin 66 that is located forward of lock bar
pivot pin 64. Connector pin 66 extends through a bore 66b in lock
bar 44 and has its opposite ends extending into bores formed in
spring members 40 and 42, respectively. Thus, one end of connector
pin 66 extends into bore 66a in spring member 40 and the opposite
end of connector pin extends into bore 66c in spring member 42.
Both bores 66a and 66c are drilled so the diameter of the bores is
only very slightly greater than the diameter of connector pin 66.
The diameter of bore 66b in lock bar 44, through which connector
pin 66 extends, is likewise only very slightly greater than the
diameter of the connector pin 66. As such, the connector pin 66
slides through the bore 66b during assembly of knife 10, yet there
is a close tolerance between the pin and the bores. As a result,
spring tension from spring members 40 and 42 is transmitted
directly to lock bar 44 via connector pin 66, and movement of lock
bar 44 as described below directly causes movement of the spring
members.
[0027] The spring members 40 and 42 are mounted in handle 12 so
that the spring members constantly apply biasing force against
adjacent structures in the "downward" direction--that is, the
direction moving from the spine of the knife 10 toward the knife
receiving slot on the opposite side of the knife. Spring members 40
and 42 are thus compressed during assembly of the knife when pin 62
is inserted into the associated bores and is connected to the
liners and handles. Pin 62 thus maintains the spring members in a
state of constant compression so that biasing force is applied by
the spring members on the blades and as detailed herein, on the
lock bar 44. If knife 10 were assembled without the secondary
blades, the spring members could be compressed by fixing the
rearward ends of the spring members (as with pins and the like)
when the spring members are assembled with pin 62.
[0028] With continuing reference to FIG. 3, the tang portion 70 of
blade 18 has a notched shoulder portion 72 that is cooperatively
shaped to receive the rearward end 74 of spring member 42 when
blade 18 is in the open position. As best seen in FIG. 4, when
blade 18 is in the open position, shoulder 72 on blade 16 abuts
rearward end 74 of spring member 42 to stop rotation of the blade
in the fully open position. Returning to FIG. 3, flattened portion
76 of tang 70 underlies spring member 42 partially along the length
of the spring member near the rearward end.
[0029] Similarly, the tang portion 80 of blade 16 has a notched
shoulder portion 82 that is cooperatively shaped to receive the
rearward end 84 of spring member 40 when blade 16 is in the open
position. Again referring to FIG. 4, when blade 16 is in the open
position, shoulder 82 on blade 16 abuts rearward end 84 of spring
member 40 to stop rotation of the blade in the fully open position.
A flattened portion 86 of tang 80 underlies spring member 40
partially along the length of the spring member near the rearward
end.
[0030] As noted above, spring members 40 and 42 are mounted in
handle 12 so that the spring members constantly apply biasing force
on the blades. With reference to blades 16 and 18, when the blades
are in the open position springs 40 and 42 apply spring force to
the blades at the interface between the springs and the flattened
portions of the tangs, 76 and 86, respectively.
[0031] The biasing force applied by spring members 40 and 42 to
blades 16 and 18 helps to hold the blades in both their open and
closed positions. As noted earlier, a flattened portion 76 of tang
70 underlies spring member 40 when blade 16 is in the open
position. In this position, spring member 40 applies biasing force
against the blade. The combination of the spring force applied by
spring member 40 with the abutting relationship between rearward
end 74 of spring member 40 in notch 72, retains blade 16 in the
open position.
[0032] Blade 16 may be moved to the closed position by rotating it
about pivot shaft 26 (e.g., rotating blade 16 in the
counterclockwise direction in FIG. 5). As this is done and tang 70
rotates, the flattened portion 76 of tang 70 pushes upwardly
against the rearward end of spring member 40. As the blade
continues its rotation in this closing direction, the tang
continues to push against the spring member, deflecting the spring
member 40 upwardly about pin 62 and thereby "loading" the spring
with greater force. Stated another way, the spring member is
applying greater biasing force on the blade as it is rotated and
the spring member is deflected away from its resting position. The
deflection of spring 40 when blade 16 is in an intermediate
position between fully opened and fully closed is shown in FIG. 1.
As the rotation continues, the lower edge of tang 70 passes the
spring member, resulting in spring force urging the blade 16 into
the closed position. When blade 16 is fully rotated to the closed
position, spring member 40 rests against and applies force to
flattened portion 78 of tang 70, thereby retaining blade 16 in the
closed position. The force applied by spring member 40 helps to
retain the blade in the closed position.
[0033] Spring member 42 acts on blade 18 in an identical manner to
that just described with respect to spring member 40 acting on
blade 16. FIG. 5 illustrates blade 18 in an intermediate position
in phantom lines, with the resulting deflection of spring member
42, and with blade 18 in the fully closed position in solid lines,
with flattened portion 88 of tang 80 resting against and abutting
spring member 42.
[0034] The tang 90 of primary blade 14 includes a notch 92 into
which a cooperatively shaped tooth 94 on the forward end of lock
bar 44 fits. As best shown in FIG. 5, when blade 14 is in the fully
open or extended position, tooth 94 is received into and engages
notch 92 in tang 90, the lock bar thus both stopping rotation of
blade 14 in the fully open position where the forward end of the
lock bar abuts the rearward facing surface of the knife tang, and
locking the blade in this position with tooth 94 and preventing the
blade from being rotated from the open and locked position toward
the closed position. It will be appreciated that the geometric
configuration of the tooth and receiving notch may take on many
different forms so long as the tooth is received positively in the
notch to lock the blade.
[0035] Operation of lock back mechanism 60 will now be detailed.
When primary blade 14 is in the closed position, tooth 94 on the
forward end of lock bar 44 presses against and is urged with spring
force against flattened portion 96 on tang 90. The forward end of
the lock bar 44 is under the biasing force applied to the lock bar
by both spring members 40 and 42 by virtue of connector pin 66--as
noted, when the knife is assembled the spring members 40 and 42
apply constant spring pressure to the associated structures. The
biasing force is applied downwardly on the forward end of the lock
bar. That is, tooth 94 is urged against flattened portion 96 of
tang 90 and therefore retains the blade 14 in the closed position
under spring force. Blade 14 may be rotated from the closed
position to the open position by grasping the exposed portion of
the blade and rotating it. As the blade rotates, tooth 94 of lock
bar 44 rides over tang 90 and the lock bar is thus deflected
against the biasing force applied by spring members 40 and 42 at
the direct connection between the lock bar 44 with springs 40 and
42 through connector pin 66. When the blade 14 is rotated to the
fully open position, tooth 94 is urged into notch 92, again under
the force applied to the lock bar by the spring members. When tooth
94 is received into notch 92, the blade 14 is locked in the open
position and may not be rotated in either direction.
[0036] Locking mechanism 60 is unlocked to allow blade 14 to be
rotated from open to closed by depressing lock bar 44 in the
notched section 46 of handle 12. When lock bar 44 is depressed in
notched section 16, the lock bar pivots about lock bar pivot pin
64--the forward end of the lock bar moves upwardly until tooth 94
disengages from notch 92. Because bores 64c and 64e in spring
members 40 and 42 are oversized, as the lock bar 44 pivots about
lock bar pivot pin 64, the connector pin 66 moves directly with the
lock bar very slightly in the upward direction. However, the lock
bar pivot pin 64 does not make contact with the spring members
where the pin passes through the oversized bores 64c and 64e in the
spring members. The oversized bores formed in the spring members
thus allow the lock bar 44 to move in an up and down direction
relative to the handle as the lock bar is depressed at notched
section 46.
[0037] Stated another way, the diameter of the bores 64c and 64e is
larger than the diameter of the lock bar pivot pin 64, and as the
lock bar pivots about the lock bar pivot pin 64, the spring member
40 and 42 apply spring force to the lock bar by virtue of direct
connection between the lock bar and the springs with lock bar
connector pin 66, but the lock bar pivot pin 64 does not contact
either spring member due to the clearance in the bores.
[0038] Once tooth 94 is disengaged from notch 92, primary blade 14
may be rotated to the closed position.
[0039] The linear distance between lock bar pivot pin 64 and
connector pin 66 may be varied to vary the force necessary to pivot
lock bar 44. Thus, by increasing the distance between the axis
through pins 64 and 66, the amount of force required to pivot lock
bar 44 increases. Conversely, by moving the pins closer together,
the force necessary to activate the lock bar decreases. The amount
of spring force applied by spring members 40 and 42 may likewise be
varied by varying the physical characteristics of the materials
used to fabricate the springs. For example, the relative "strength"
of the springs may be changed by using different metals, or by
changing the thickness of the springs.
[0040] It will be appreciated that the mechanism described herein
and illustrated in the figures applies downward, locking force on
the lock bar 44 by the spring members urging the forward end of the
lock bar, forward of the connector pin 66. This structure allows
the rearward end of the knife to be relatively free from other
structures that might be associated with more conventional lock
back mechanisms, and thus allows, for example, inclusion of the two
minor blades 16 and 18 at the rearward end of the knife. The lock
back mechanism 60 therefore allows for a reliable lock for the
primary blade in a Whittler Pattern knife.
[0041] It will also be appreciated that various design
modifications may be made without departing from the nature and
scope of the invention. For example, the two minor blades 16 and 18
may be omitted and the springs 40 and 42 may in that case be
supported at their rearward ends by the liners and/or the spacer
bar. Moreover, while the handle 12 of knife 10 preferably includes
liners 28 and 30 as separate pieces, the handle 12 may be
manufactured without separate liners. Accordingly, the knife term
"handle" as used herein contemplates a handle with liners, and a
handle without liners. Finally, it will be appreciated that
structure of the spring members may be varied from the form
described herein and shown in the drawing figures. As one example,
the liner members may be cut longitudinally from the forward end
toward the rearward end to define spring members in the liners
themselves--the forward end of the cut is open and the rearward end
of the cut is closed to define a spring. This allows each spring
member and liner to be fabricated from a single piece of
material.
[0042] While the present invention has been described in terms of a
preferred embodiment, it will be appreciated by one of ordinary
skill that the spirit and scope of the invention is not limited to
those embodiments, but extend to the various modifications and
equivalents as defined in the appended claims.
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